444 DR. ERIC DRABBLE ON THE 
In the present investigation the method of junction has been worked out in Kentia sp., 
Latania borbonica, and Dictyosperma album. In all these the phenomena presented are 
similar, 
A transverse section taken through the stem in the region of connection shows a 
series of stem-bundles with internal scattered protoxylem followed externally by more 
densely packed metaxylem, and this in turn by the thin-walled phloem (PI. 51. fig. 89). 
In the ground-tissue separating these bundles run strands of xylem and phloem 
pursuing a somewhat sinuous course and at their inner extremities establishing 
connection with the xylem and phloem of the stem-bundles, some of which are 
peripherally, some deeply placed (Pl. 51. fig. 90). The xylem-elements of these strands 
are continued into the xylem-portion of the stem-bundles laterally and follow the course 
of this bundle as constituent elements of it. | 
In the same way the sieve-tubes pass into the phloem-portion of the stem-bundles 
(Pl. 51. fig. 89). 
These strands may be followed externally into the young root arising in the pericycle, 
as distinct procambial strands (PI. 48. fig. 1). 
In transverse sections of mature roots close to the base (7.e., just external to the 
pericycle of the stem), the centre is occupied by a number of free strands of fibrous 
tissue surrounding in the form of sheaths the xylem- and phloem-elements. 
The xylem- and phloem-groups in each strand are radially arranged, with exarch 
protoxylem.. Thus in this region, traversing the ground-parenchyma of the root, occurs 
not one but a series of cylinders each with a root-like structure. 
The endodermis is not well-marked in this region of the root, but may sometimes be 
seen as an incomplete ring round several of the more external strands. 
Some of the strands are very small and contain only a single xylem- and a single 
phioem-group (Pl.51. fig. 101). "These are the individual bundles, each of which is 
proximally connected with a single bundle of the stem. Distally, by fusion with one 
another, they give rise to the radially symmetrical cylinders of this region of the root. 
The latter again in turn fuse with one another and give larger cylinders with irregular 
outline and irregularly arranged xylem and phloem. Usually the more peripheral 
cylinders are the first to fuse, the central ones often remaining as free strands even in 
the fully developed root. The peripheral cylinders by their fusion give rise to a series 
of ineurved ares as seen in transverse section, sometimes completed internally, when 
they enclose a central strand of ground-parenchyma continuous above with the common 
ground-tissue of the root (Pl. 51. figs. 91 & 92). 
By progressive fusion, the number of free strands becomes successively reduced in the 
more distal region. The closed rings of fused strands with central ground-tissue again 
fe out internally and the edges fuse with those of neighbouring cylinders, and in this 
TA complete but deeply lobed ring is formed (PL 51. figs. 94 & 98). This always 
remains longest incomplete on the adaxial side. The lobes become gradually more 
shallow in the distal region, until eventually a simple non-lobed central eylinder of 
normal root nature is established. 
In most roots these changes in the vascular anatomy are completed in that portion of 
